A three-dimensional Eu(III) framework in the crystal structure of dimethylaminium poly[dimethylformamide-κ1 N)bis(μ4-terephthalato-κ4 O:O′:O′′:O′′′)europium(III)] monohydrate, C21H25EuN2O10

C21H25EuN2O10, monoclinic, P21/n (no. 14), a = 14.1635(8) Å, b = 12.1381(6) Å, c = 14.4528(7) Å, β = 104.361(2)°, V = 2407.1(2) Å3, Z = 4, Rgt (F) = 0.0304, wRref (F 2) = 0.0893, T = 296 K.

In Situ Ligand Formation in the Synthetic Processes from Mononuclear Dy(III) Compounds to Binuclear Dy(III) Compounds: Synthesis, Structure, Magnetic Behavior, and Theoretical Analysis

Guided by the self-assembled process and mechanism, the strategy of in situ Schiff base reaction would be capable of bringing a feasible method to construct and synthesize lanthanide compounds with distinct structures and magnetic properties. A mononuclear Dy(III) compound was synthesized through a multidentate Schiff base ligand and a chelating β-diketonate ligand, which was named as [Dy(L)(bppd)]·CH₃OH [1; H₂L = N,N'-bis(2-hydroxy-5-methyl-3-formylbenzyl)-N,N'-bis(pyridin-2-ylmethyl)ethylenediamine and bppd = 3-bis(pyridin-2-yl)propane-1,3-dione]. Furthermore, a new binuclear Dy(III) compound, [Dy₂(H₂Lox)(bppd)₃]·8CH₃OH [2; H₄Lox = N,N'-bis[2-hydroxy-5-methyl-3-(hydroxyiminomethyl)benzyl]-N,N'-bis(pyridin-2-ylmethyl)ethylenediamine], was obtained via an in situ synthetic process. Under similar synthetic conditions, [Dy(L)(ctbd)] [3; ctbd = 1-(4-chlorophenyl)-4,4,4-trifluoro-1,3-butanedione] and [Dy₂(H₂Lox)(ctbd)₃]·CH₃OH·C₄H₁₀O (4) were synthesized by modifying the β-diketonate ligand and in situ Schiff base reaction. Compound 3 is a mononuclear configuration, while compound 4 exhibits a binuclear Dy(III) unit. Therein, formylbenzyl groups of H₂L in 1 and 3 were changed to (hydroxyiminomethyl)benzyl groups in 2 and 4, respectively. In isomorphous 2 and 4, two Dy(III) centers are connected through two phenol O^- atoms of the H₂Lox^2- ligand to form a binuclear structure. Eight-coordinated Dy(III) ions with different distortions can be observed in 1-4. The crystals of 1 and 3 suffered dissolution/precipitation to obtain 2 and 4, respectively. The relationship between the structure and magnetism in compounds 1-4 was discussed through the combination of structural, experimental, and theoretical investigations. Especially, the rates of quantum tunneling of magnetization of 1-4 were theoretically predicted and are consistent with the experimental results. For 2 and 4, the theoretically calculated dipolar parameters J_dip are consistent with the experimental observation of weak ferromagnetic coupling.

A new family of dinuclear lanthanide complexes exhibiting luminescence, magnetic entropy changes and single molecule magnet behaviors

Four isomorphic and dinuclear lanthanide complexes were synthesized. Complexes Eu^III and Tb^III exhibit strong emissions, while Gd^III shows the magnetocaloric effect and Dy^III displays a single-molecule magnet.

A dinuclear Eu(III) complex in the crystal structure of dodecaaqua-bis(μ2-4-(1H-tetrazol-5-yl)benzoato-κ2 O:O′) bis(5-(4-carboxylatophenyl)tetrazol-1-ide) tetrahydrate, C32H50Eu2N16O24

C32H50Eu2N16O24, monoclinic, P21/c (no. 14), a = 7.685(5) Å, b = 13.482(5) Å, c = 23.240(5) Å, β = 93.578(5)°, V = 2403.2(19) Å3, Z = 2, R gt(F) = 0.0235, wR ref(F 2) = 0.0577, T = 293 K.

Assembling two Dy2 single-molecule magnets with different energy barriers via fine-tuning the geometries of DyIII sites

Two Dy₂ single-molecule magnets are prepared. The energy barrier of 2 is slightly enhanced by adjusting the geometries of Dy^III centers.

Rationally assembled nonanuclear lanthanide clusters: Dy9 displays slow relaxation of magnetization and Tb9 serves as luminescent sensor for Fe3+, CrO42− and Cr2O72−

The utilization of a Schiff base ligand 2-((2-hydroxy-4-methoxy-benzylideneamino)methyl)phenol (H₂L) afforded five nonanuclear lanthanide(iii) clusters. Dy₉ displays slow relaxation of magnetization and Tb₉ serves as luminescent sensor for Fe³⁺, CrO₄²⁻ and Cr₂O₇²⁻.

Yb3+ can be much better than Dy3+: SMM properties and controllable self-assembly of novel lanthanide 3,5-dinitrobenzoate-acetylacetonate complexes

Novel Ln 3,5-dinitrobenzoates were studied; the Δ_eff value of the Yb derivative is the highest known one for binuclear complexes of this Ln.

Single molecule magnetic behaviour in lanthanide naphthalenesulfonate complexes

A family of mononuclear lanthanide complexes exhibiting slow magnetic relaxation is reported, providing the first examples of pure 4f sulfonate-based single molecule magnets.

Experimental and theoretical interpretation of the magnetic behavior of two Dy(iii) single-ion magnets constructed through β-diketonate ligands with different substituent groups (–Cl/–OCH3)

Two Dy(iii) single-ion magnets, formulated as [Dy(Phen)(Cl-tcpb)₃] (Cl-1) and [Dy(Phen)(CH₃O-tmpd)₃] (CH₃O-2) were obtained through β-diketonate ligands (Cl-tcpb = 1-(4-chlorophenyl)-4,4,4-trifluoro-1,3-butanedione and CH₃O-tmpd = 4,4,4-trifluoro-1-(4-methoxyphenyl)-1,3-butanedione) with different substituent groups (–Cl/–OCH₃) and auxiliary ligand, 1,10-phenanthroline (Phen). The Dy(iii) ions in Cl-1 and CH₃O-2 are eight-coordinate, with an approximately square antiprismatic (SAP, D_4d) and trigonal dodecahedron (D_2d) N₂O₆ coordination environment, respectively, in the first coordination sphere. Under zero direct-current (dc) field, magnetic investigations demonstrate that both Cl-1 and CH₃O-2 display dynamic magnetic relaxation of single-molecule magnet (SMM) behavior with different effective barriers (U_eff) of 105.4 cm⁻¹ (151.1 K) for Cl-1 and 132.5 cm⁻¹ (190.7 K) for CH₃O-2, respectively. As noted, compound CH₃O-2 possesses a higher effective barrier than Cl-1. From ab initio calculations, the energies of the first excited state (KD₁) are indeed close to the experimental U_eff as 126.7 cm⁻¹vs. 105.4 cm⁻¹ for Cl-1 and 152.8 cm⁻¹vs. 132.5 cm⁻¹ for CH₃O-2. The order of the calculated energies of KD₁ is same as that of the experimental U_eff. The superior SIM properties of CH₃O-2 could have originated from the larger axial electrostatic potential (ESP_(ax)) felt by the central Dy(iii) ion when compared with Cl-1. The larger ESP_(ax) of CH₃O-2 arises from synergic effects of the more negative charge and shorter Dy–O distances of the axial O atoms of the first sphere. These charges and distances could be influenced by functional groups outside the first sphere, e.g., –Cl and –OCH₃.

Further studies from the viewpoint of electrostatic potential demonstrate that the larger axial electrostatic potential (ESP) felt by the central Dy (iii) ion of CH₃O-2 is responsible for its better SIM property when compared with Cl-1.

Metal-Organic Framework of Lanthanoid Dinuclear Clusters Undergoes Slow Magnetic Relaxation

Lanthanoid metal-organic frameworks (Ln-MOFs) can adopt a variety of new structures due to the large coordination numbers of Ln metal ions, and Ln-MOFs are expected to show new luminescence and magnetic properties due to the localized f electrons. In particular, some Ln metal ions, such as Dy(III) and Tb(III) ions, work as isolated quantum magnets when they have magnetic anisotropy. In this work, using 4,4′,4″-s-triazine-2,4,6-triyl-tribenzoic acid (H₃TATB) as a ligand, two new Ln-MOFs, [Dy(TATB)(DMF)₂] (1) and [Tb(TATB)(DMF)₂] (2), were obtained. The Ln-MOFs contain Ln dinuclear clusters as secondary building units, and 1 underwent slow magnetic relaxation similar to single-molecule magnets.

A series of anionic host coordination polymers based on azoxybenzene carboxylate: structures, luminescence and magnetic properties

Series of luminescent or magnetic coordination polymers based on azoxybenzene tetracarboxylic acid and bipyridine have been afforded, and characterized systematically.

Novel mononuclear Ln complexes with pyrazine-2-carboxylate and acetylacetonate co-ligands: remarkable single molecule magnet behavior of a Yb derivative

A series of novel mononuclear complexes were prepared, and the Yb derivative exhibits the highest Δ_eff/k_B value known for ytterbium complexes.

Phenalenyl-based mononuclear dysprosium complexes

The phenalenyl-based dysprosium complexes [Dy(PLN)2(HPLN)Cl(EtOH)] (1), [Dy(PLN)3(HPLN)]·[Dy(PLN)3(EtOH)]·2EtOH (2) and [Dy(PLN)3(H2O)2]·H2O (3), HPLN being 9-hydroxy-1H-phenalen-1-one, have been synthesized. All compounds were fully characterized by means of single crystal X-ray analysis, paramagnetic (1)H NMR, MALDI-TOF mass spectrometry, UV-vis spectrophotometry and magnetic measurements. Both static (dc) and dynamic (ac) magnetic properties of these complexes have been investigated, showing slow relaxation of magnetization, indicative of single molecule magnet (SMM) behavior. Attempts to synthesize sublimable phenalenyl-based dysprosium complexes have been made by implementing a synthetic strategy under anhydrous conditions. The sublimed species were characterized and their thermal stability was confirmed. This opens up the possibility to deposit phenalenyl-based lanthanides complexes by sublimation onto surfaces, an important prerequisite for ongoing studies in molecular spintronics.

Dysprosium(iii) complexes with a square-antiprism configuration featuring mononuclear single-molecule magnetic behaviours based on different β-diketonate ligands and auxiliary ligands

Three mononuclear SMMs derived from three β-diketonate ligands and auxiliary ligands have been synthesized.

Highly pH-dependent synthesis of two novel three-dimensional dysprosium complexes with interesting magnetic and luminescence properties

Two unprecedented Dy-MOFs with interesting magnetic and luminescence properties were obtained using identical starting materials and method but at different pH values.

Magnetic and luminescent properties of lanthanide coordination polymers with asymmetric biphenyl-3,2′,5′-tricarboxylate

An asymmetric ligand was employed to construct eight (3,6)-connected lanthanide complexes exhibiting slow magnetization relaxation behaviour and characteristic luminescent properties.

A Dy2 single-molecule magnet with benzoate anions and phenol-O− bridging groups

A Dy₂ single-molecule magnet, namely [Dy₂(H₃L)₂(PhCOO)₄]·4H₂O (1), was obtained from the reaction of Dy(PhCOO)₃ with 1,5-bis(2-hydroxy-3-methoxybenzylidene)carbonohydrazide (H₄L).

Acetato-bridged dinuclear lanthanide complexes with single molecule magnet behaviour for the Dy2 species

Five dinuclear Ln complexes bridged by acetate groups in the η¹:η²:μ₂ mode are reported with the Dy₂ analogue behaving as a SMM.

Three novel 1D lanthanide-carboxylate polymeric complexes: syntheses, crystal structures and magnetic analyses

Three novel one-dimensional (1D) lanthanide coordination complexes involving the 4-methyl-3-nitrobenzoic acid (HL) ligand, with the general formulae [Gd(L)3(H2O)(CH3OH)] (1), [Gd(L)3(H2O)2]·(4,4'-bpy)·CH3OH (2), [Dy(L)3(H2O)(CH3OH)] (3), have been synthesized by solvothermal reactions. These complexes have been structurally characterized by single-crystal X-ray diffraction, IR, PXRD, TGA, and elemental analysis. Complexes 1 and 3 are isostructural except for the distinction of the metal ion. Magnetic measurements indicate that complexes 1-3 show antiferromagnetic behaviors. Complex 3 behaves with slow relaxation of the magnetization, where the frequency-dependent out-of-phase signals are noticed. However, the characteristic maxima were not reached above 2 K under zero direct current (DC) fields. When a DC field of 5000 Oe was employed, the frequency dependent peaks of alternating current (AC) signals were obtained.